Service life assessment of CFRP mooring lines for floating offshore platforms

The increasing demand for offshore platforms presents critical challenges to the mechanical properties and sustainability of the classical mooring systems, motivating the need to explore the possibilities of using Carbon Fiber Reinforced Polymer (CFRP) as the mooring material. A reliable service-life prediction model is essential for maintaining the structural integrity of the CFRP mooring system. This paper focuses on developing a probabilistic model for predicting the service life of CFRP mooring lines by considering accumulated fatigue damage and seawater absorption induced degradation. The basic assumption of this model is that the fatigue life of CFRP unit cell fulfills Weibull distribution, and that the fatigue strength of the unit cell and mooring cable fulfills the serial-parallel model. The uncertainties of the service-life associated with the large variety of sea conditions are further taken into account through hydrodynamic analysis based dynamic loading estimation. Another feature of this model is that it could predict residual service life during the service period by taking the structural health monitoring (SHM) data as input to estimate the accumulated damage. Furthermore, this model is used to evaluate the CFRP mooring design for a full-scale in-service offshore platform. The results show that the predicted service life of the designed CFRP mooring lines exceeds the 30-year design service life under the target environmental conditions.